In the field of analogue to digital converters (ADCs), the accuracy of an ADC channel may be significantly impacted by an excessive pad voltage and, thus, an injection current. Such an excessive pad voltage may be caused by a short circuit or an Electrostatic Discharge (ESD) event, even if such an event occurs on an adjacent or nearby channel. Typically, excessive pad voltages and injection currents are limited by protection circuitry, such as ESD clamping diodes, external series resistors, etc. However, whilst such protection circuitry may be sufficient to provide a level of protection against damage caused by excessive pad voltages and injection currents, such protection circuitry is not capable of completely masking the effects of such events. Accordingly, when a fault condition, such as a short circuit to a supply voltage occurs, or an ESD event occurs, resulting in a larger than expected current being injected into an ADC pin, such an event will have a significant influence on the input signal of the ADC. In some instances, this affects the accuracy of the signal output by the ADC, despite the provision of protection circuitry. Furthermore, pads in close proximity to such an event, and particularly adjacent pads, may be affected by excessive voltage/injection current due to potential secondary effects of localised supply rail droop/surge.
ESD events, etc. tend to be of a short duration, and as such their effects typically dissipate relatively quickly, enabling normal operation of, in this scenario, the ADC to resume. However, corrupt output values from the ADC, as caused by an ESD event, etc., will have been provided to other circuitry such as, say, signal processing logic or the like, which rely on the values output by the ADC to perform their respective functions. Thus, the corrupt values provided by the ADC as a result of an ESD event or the like may cause inappropriate functioning of the system that relies on the values output by the ADC.